TEHRAN >> The pastry shop, tucked away in an affluent west Tehran neighborhood and selling Disney-themed cakes and party hats, is not particularly notable except for one thing: It is owned and operated by Iran’s powerful Ministry of Petroleum.

The shop — along with luxury cars, an airline and dozens of other pricey assets — was seized by the government from Babak Zanjani, a 43-year-old billionaire businessman who for more than a decade was a major figure in Iran’s sanctions-busting network and this month received a death sentence for his dealings.

Zanjani’s arrest in 2013, after President Hassan Rouhani came to power, was portrayed as a symbolic break with the high levels of corruption that defined the years under the presidency of Mahmoud Ahmadinejad, from 2005 to 2013. His conviction, by a lower court, was an attempt to show the Iranian public that, with the lifting of sanctions in January, the days of the sanctions-skirting middlemen are over.

Reconnecting Iran to the world economy is a top priority for Rouhani. But to fully reconnect, Iran needs to dismantle the network of thousands of intermediaries that was devised to get around the sanctions. The problem, economists and insiders say, is that enough sanctions remain in place that the Iranian economy still cannot function without the network.

The government has taken some steps. The Ministry of Petroleum is working on a new, more competitive model for its oil contracts, and the Parliament signed a bill to fight money laundering, an important step toward more financial transparency.

But there is only so much it can do. Regular financial transactions continue to be nearly impossible because the United States has designated the Islamic Republic a “state sponsor of terrorism,” stemming from its support for the Lebanese Hezbollah movement. International banks doing business with Iran can face up to a billion dollars in penalties if they violate regulations.

“The financial hegemony of the United States is so influential that European banks are scared to work with us,” said Saeed Laylaz, an economist close to the Rouhani government. “We also don’t have enough dollars in foreign bank accounts, no international credit, so obviously some former sanction breakers continue to have an intermediary role.”

Iran has another reason to not dismantle the network too hastily. The middlemen it funneled money to for purchases around the world are sitting on billions of unspent dollars. Getting that money back is proving to be extremely difficult, experts say, and will only get harder if the network is dismantled. One financial consultant who requested anonymity because of his dealings with Iranian banks said the problem was exacerbated by a lack of record keeping.

Laylaz estimates that between 5,000 and 10,000 people worked in the network, handling deals worth between $300 billion and $400 billion over the past decade.

“At least 10 percent was taken for commissions,” he said, adding that that number did not include the money still controlled by those in the network, given to them by banks and even government institutions to do business.

With a state-run economy and billions of dollars in oil money in the hands of the government, corruption has always been a problem in Iran, said Mousa Ghaninejad, an economics professor of economy at Shahid Beheshti University in Tehran.

“But nearly a decade of sanctions has intensified the potential of corruption,” Ghaninejad said.

Quasi-state companies were given the task of evading the sanctions, and with the assistance of people like Zanjani made sure the country would keep running.

As sanctions slowly started to bite in 2006, Zanjani set up a worldwide web of dozens of front companies, operating out of Istanbul, Bangkok and Tashkent, Uzbekistan. Iranian state and private businesses would order goods from Zanjani in Iran, and he would have his foreign companies purchase virtually anything: concrete, food staples, airplanes. The merchandise would be funneled back to Iran, and he took commissions on the sales.

When Europe stopped buying Iranian oil in 2012 and the United States started to pressure top Asian buyers, Zanjani and numerous others found ways to sell Iranian crude on the black market. He would send tankers to deserted bays along the coast of Indonesia, for instance, where they would transfer the oil to other ships to hide its origins.

A lot of money changed hands, and “a lot of that money is wasted and gone forever,” Ghaninejad concluded.

But some might still be recoverable.

That is where Zanjani comes in, his grim fate supposedly a warning to others in the network to return unspent funds to the government. But the picture is not as clear as officials might like to think, and their ability to intimidate Zanjani — and, by extension, others in the network — is clearly limited.

As his case was heard in November, Zanjani, wearing striped prison pajamas, threatened to release information on corruption by government officials, said the $2 billion the courts say he owes the Ministry of Petroleum was “chump change” for him and added that he would have any sentence overturned on appeal. On that last point legal analysts agree, saying his death sentence is likely to be commuted after he repays the $2 billion.

A spokesman for Iran’s judiciary, Gholamhossein Mohseni-Ejei, virtually confirmed as much after the death sentence was handed down. Zanjani had missed many deadlines for repaying the funds, he said, “but clearly, if he does return the money, this will have influence on his sentence.”

© 2016 The New York Times Company