The simple answer would be to say that early communist thinkers larger rejected Confucianism. You could easily tie the rise of communist ideology to the "New Culture Movement" and the May Fourth Movement. A bit of background:

In the late 19th and early 20th century it was clear to most informed thinkers that the Qing state was cracking round the edges and that China was in a subordinate position relative to any number of foreign powers, both western states like Britain that had soundly defeated Chinese forces in the two opium wars, and the boxer rebellion, but also Japan, especially after China's defeat in the Sino-Japanese war in 1895. (One of the results of which was that China ceded control of Taiwan and the Liaodong peninsula to Japan. Japan reluctantly relinquished control over Liaodong after pressure from Russian, Germany and France.) The Qing, after a rough century finally collapsed in 1911. Chinese thinkers sought explanations for why China had seemingly fallen from grace. China had traditionally thought of itself as the epitome of culture and civilization, as exemplified by the, obviously superior, Chinese intellectual traditions. Many of the early 20th century thinkers came to the conclusion that this was simply wrong. Many argued that the first step in reforming the Chinese state to make it stronger was to reform Chinese culture. All of this came to a political head on May 4th 1919. China had actually sent nearly 100,000 people to aid in the WWI war effort on the side of the allies, in the hopes that they could use their aid as a basis to renegotiate unfair treaties with the western powers. When Versailles came, the Chinese delegates were kept out of the meeting. On May 4th the results of the treaty became known in China; not only was China not placed on equal footing with the west, but German controlled territories in China were ceded to Japan after Germany's defeat. Young intellectuals took to the street.

One of the most significant figures throughout the new culture and may fourth movements was co-founder (or at the time, future co-founder) of the Chinese Communist Party, Chen Duxiu. Chen had real credentials as a reformer. One issue that came up a lot at the time was language reform. Before the early 20th century most writing in China was done in Classical Chinese. The relation between Classical Chinese and modern vernacular Chinese is sometimes likened to that between a modern European language and Latin. Classical Chinese was modeled after the language of the Confucian classics, already 2000 years old, and bore little resemblance to what the average person would have spoken. There was a movement to do away with classical Chinese and write in something closer to spoken Chinese because thinkers thought it would be easier to learn and help improve literacy rates and allow more people to educate themselves and participate in the political process. Chen was an early adopter, publishing a vernacular newspaper in Anhui even before the movement really picked up. He also advocated for a rejection of Chinese philosophy and the adoption of science and democracy from the west. He is still remembered for anthropomorphizing the concepts as 'Mr. Science' and 'Mr. Democracy'. His and other early Chinese communists' adoption of Marxist philosophy is in no small way related to their search for some external, non-Chinese set of political constructs that they hoped would work better.

Going forward, Maoist discourse also didn't look kindly on Confucianism. To Mao, Confucius was a tool of feudal society, helping the rulers control the masses.

Now, there were interesting ways in which traditional Chinese thought interacted with early Chinese communism. One example might be agrarian reformer Liang Shuming who was, at least tentatively, aligned with the communists for a time and enjoyed personal audiences with Mao on multiple occasions (he eventually became very critical of the regime and fell out of political favor). Liang was a self described Confucian and, indeed, Guy Alitto's excellent biography of him is actually called "The Last Confucian". Liang did not, however, call himself a communist and most that did were highly critical of traditional Chinese thought.

For more on Chen Duxiu and the era, I recommend the book "Chen Duxiu: Founder of the Communist Party" by Lee Feigon and Maurice Meisner's book "Li Ta-chao and the origins of Chinese Marxism" which is about Li Dazhao, the other founder of the CCP.